#3
GM7 would sound good after the Dsus4.
♪♫♪
92% percent of the teen population would be dead if Hollywood said it wasn't cool to breathe anymore.
Put this in your signature if you are one of the 92% who wouldn't be breathing.
#4
That's a progression in D Major so you could use:
D
Em
F#m
G
A
Bm
C#dim

Or some of the derivatives, like for example the Dsus4 or the Gmaj7 that were proposed..

Cheers!
ZeG